Partial sums of A051836.

Terms

a(0) =1a(1) =9a(2) =42a(3) =140a(4) =378a(5) =882a(6) =1848a(7) =3564a(8) =6435a(9) =11011a(10) =18018a(11) =28392a(12) =43316a(13) =64260a(14) =93024a(15) =131784a(16) =183141a(17) =250173a(18) =336490a(19) =446292a(20) =584430a(21) =756470a(22) =968760a(23) =1228500a(24) =1543815a(25) =1923831a(26) =2378754a(27) =2919952a(28) =3560040a(29) =4312968